CDG: A Formal Theory for Graph-Oriented Visual Programming of Distributed Systems

The graph-oriented programming model (GOP) [4] aims at providing high-level abstractions for programming distributed system. In GOP, a language-level graph construct, consisting of user-specified logical graphs and the distributed implementation of various kinds of graph operations, is used as the underlying mechanism for programming the configuration, communication, and synchronization of the program components. The programmer is given enough flexibility to specify and exploit the semantics of the graph construct to deal with different aspects of distributed programming in an integrated way. In this paper we present a formal theory, called the calculus of distributed programming graph (CDG), which formally characterizes the language-level graph construct. Serving as a formal basis for the specification of the fundamental operations on the user-specified graphs, CDG is used as an operational semantic model for a visual programming environment on top of the graph oriented programming platform.